It is common to provide levers with various arrangements for mechanical advantage so that a minimum amount of force is required to achieve the pivot of a lever and to thus accomplish the desired work or actuation for controlling mechanical apparatus or for like purposes. In those arrangements, it is very common to employ a long lever for maximum torque and having a short lever arm so that a minimum of force is required by an operator to manually manipulate that type of lever. However, the physical limitations on the length of the lever arm, and the limitations on the amount of space and material available for the lever arm enter into the considerations for making a long lever arm. That is, there are requirements for the employment of levers where it is desirable that the operator not be required to exert a considerable force in order to accomplish the desired work through the lever, and such considerations are also important where repeated lever action is required and operator fatigue is a factor.
Further, powered types of levers are commonly used in the mechanical arts, and such use no doubt could be in the nature of a powered apparatus which is controlled through a control of the flow of the energy or power to the apparatus itself which in turn causes the lever or linkage to move and thus actuate the mechanism, all as desired. However, in that type of installation, the powered apparatus would be the complete and sole control of the lever or linkage, and the operator would have no means of sensing the exact degree of actuation of the mechanism and would therefore lose control in the human sensing of exactly what action the lever is undertaking.
Accordingly, the present invention provides an arrangement for a lever wherein both manual and powered force is applied to the lever and against a resistance, for achieving the work or action at the point of the resistance, such as in the actuation of a valve which has an inherent resistance which must be overcome before actuation occurs. That is, a valve of the spool type has return springs and also internal pressures which resist the movement of a control lever, and normally the operator is required to manually overcome that resistance, rather than have any powered apparatus to over-come the resistance in conjunction with manual control.
Therefore, the present invention provides a lever with a powered accessory which is used to reduce the manual effort required to actuate mechanisms having large resistances or which require frequent actuation against a resistance and thus induce operator fatigue.
Further, it is an object and advantage of this invention to accomplish the aforementioned and to do so with an arrangement of a manually controlled lever having a powered accessory and with the entire arrangement being such that the lever can be retained in a set operative position without necessarily requiring the hand contact by the operator, and the lever can also be readily returned to a neutral position and retained in that position.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.